1.) Create a Virtual SD Card using the Virtual SD Card Maker program. You can go as low as 64 MB or as high as 2 GB, though 2 GB is highly recommended (I believe you can use a cmd function to make the file over 2 GB, but this is just for the basics). Make sure the file produced is named sd.raw and place the file under "C:\Users\*Name*\Documents\Dolphin Emulator\Wii". If there's already an sd.raw file in there, delete it before inserting your newly created file.

2.) Open WinImage and open your sd.raw with it. At this point, you should have all of your files, codes, and Gecko OS inside their respective folders as if you were going to use a Wii. You would also place everything into a dummy folder (Just create a new folder and put everything in it). In WinImage, go to Image > Inject a Folder and search for your dummy folder before injecting it. Save and close afterward. You'll also need to place the boot.elf file from Gecko OS into a folder of your choice.

Note: If you dumped your NAND and are using it with your Dolphin build, then you don't need to download and install IOS 36, since it was more than likely already installed into your Wii's NAND prior to dumping, in which you can skip this step and go straight to Step 5.

4.) Open Dolphin, and go to Tools > Install WAD and open the IOS 36 WAD you downloaded from Step 3 with it.

5.) Once you've installed IOS 36, right click on your Brawl ISO entry before clicking on "Set as Default IS0." After that, open up Config, go to Wii, and make sure Insert SD is enabled.

6.) To boot modded Brawl though Dolphin, you can do one of two things. Though before starting the game, make sure you configure Gecko's Hook Type to be AXNextFrame.

6a.) Click Open before searching for your saved boot.elf file.

6b.) Browse for the folder that contains your saved boot.elf like if you're going to add a new IS0. This entry will stay in your Dolphin window for quicker access.

If there's anything else that needs to be added, let me know, and I'll update with misc information/fixes.

A Wii NAND dump should include IOS 36 so that will avoid the problem altogether. Users without a NAND dump will need to manually install IOS 36 on Dolphin 5.0-5934 and later. There was also a time before 5.0-5934 when IOS 36 was unneeded but that relied on guesswork that caused a lot of unwanted problems.

I am aware that the netplay community likes to set specific builds for players to use but this information should be stated here in the event of updating their suggested build.

Also, I'm not sure where the 5.0-2712 information came from but I use the latest Dolphin Development version (5.0-6179 at the time of writing this) and update frequently. I updated my forum signature since this isn't the first time I've posted information about Dolphin.

I'm pretty sure it isn't required on the stable release of 5.0, though. I walked someone through the process of setting up mods on Dolphin 5.0 who hadn't used Dolphin before (and clearly doesn't have a NAND dump). Worked just fine for him.

EDIT: Tried out 5.0-6208. Installed IOS36 but Dolphin spits out an error message upon trying to load Gecko OS 'Invalid read from 0x0000000c, PC = 0x80e4ee9c' which keeps popping up after closing it, forcing me to end Dolphin's process.

The "Invalid read" messages sometimes appear when I start Gecko OS but the problem has already been documented in the above links. A workaround in Dolphin is to go to Config -> Interface tab -> uncheck "Use Panic Handlers"

This disables panic handlers but we don't want users to do that unless they really need to as panic handlers can provide helpful information for freezes and crashes.

Also, if you're experiencing freezes or crashes after disabling panic handlers then something else in your setup is probably the problem.

6 month old necro, I know, but I've since updated the OP to add instructions on how to download and install IOS 36 into your Dolphin (snagged from a thread on the Dolphin Forums). However, if you've dumped your NAND and are using it with your Dolphin, then you don't need to follow the additional step, as IOS 36 is already present.

I could follow most of this fairly easily, but I don't know what you mean with "At this point, you should have all of your files, codes, and Gecko OS inside their respective folders as if you were going to use a Wii". I tried searching on google, but all the tutorials I found were either very old or weren't that clear to me. Can you explain this to me please?

That is what my problem is; I don't know which files go where, and some tutorials I found on the internet talked about files which I don't have.sorry if this is actually pretty easy to solve, but this is my first time modding.